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develop, they do not thrive in a sustained population (the caprice of agroecosystem development eradicates conditions needed for population maintenance within a generation or two). These organisms are usually included in the lists of species in a region and are often used to demonstrate that a species is not threatened with extinction—even though it is (Janzen, 1972). Agroscapes, seemingly still supporting long lists of widespread species, are primed for massive extinction as individuals of these species senesce or are killed through intensification of contemporary agriculture. If all these species were to be physically removed as soon as they have no future, the catastrophe would be much more noticeable and would therefore arouse the sentiments normally associated with massive extinction.
The dry forest is more prone to these less visible catastrophes than is the rain forest, in which scraps of vegetation left when the forest is cleared die more quickly than do those of the dry forest. Thus the threatened plant species in dry forest are available for a longer time and can be used as basic stock in restoration projects (though the price paid is that they dilute the visual impact of a largely demolished forest).
A Central American tropical dry forest wildland that is large enough to be visited and used by humans is substantially larger than a wildland that is to exist without human intrusion. Tropical habitats are very rich in behaviorally sensitive species and species that exist in low-density populations. Moreover, dry forests contain many small habitats (e.g., springs, dry ridge tops, marshes, edaphic outcrops, temporary streams, and pickets of forest sheltered from the wind). Visitors (tourists researchers, seed collectors, and habitat managers) will perturb ecological interactions substantially more and effect them more permanently in dry forests than in most extra tropical or rain forest habitats. This calls for strict zoning for habitat use and replicate habitats, both of which can be compatible with conservation management only if a large acreage is set aside.
Ignore the voice that demands that a monetary value be placed on a wildland or a species before it can be conserved. Is that what you would do to determine the need for a public library, a public hospital, a public school? Can you tell me the dollar value of these institutions to your children? Are we to continue to be led by commercial interests to sanctify the production of material goods? The great majority of tropical humans live as draft animals; they are sold to the highest bidders along with the habitats that maintain them, and the purchasers are not generally benevolent. Through the swirl of changing market values, there will eventually come a day when the living organisms in a tropical wildland would be as doomed as would be libraries, if books were valued only for their paper pulp and the price of paper pulp were to rise.
Many organisms we believe to be safe are really endangered, and those we call endangered are in reality extinct. Guards will not save tropical wildlands. The world’s dry tropics are already way beyond their capacity for accommodating human activity. Thus a contract between managers of wildlands and society is mandatory. And the scientific community must aggressively participate in writing and executing